Mineral

Turquoise

Hydrated phosphate of copper and aluminium: CuAl6(PO4)4(OH)8·4H2O

Hardness: 5-6 (Mohs scale), Color: Sky-blue to apple-green, Luster: Waxy to subvitreous, Crystal Structure: Triclinic (usually cryptocrystalline), Cleavage: Perfect (rarely seen), Specific Gravity: 2.6–2.9

Identified March 20, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. Typically found in arid regions within volcanic host rocks or sedimentary layers containing copper and phosphate.

Uses & applications

Primarily used as a gemstone for jewelry (beads, cabochons, inlay) and ornamental carvings. Also highly valued as a collector's specimen.

Geological facts

Turquoise is one of the oldest known gemstones, used by Ancient Egyptians and Native Americans for over 3,000 years. The color is derived from copper (blue) and iron or chrome (green).

Field identification & locations

Identify by its unique sky-blue hue and host rock matrix (veins of black or brown). Common locations include Iran, Southwestern USA (Arizona, Nevada), and China. Collectors should look for 'natural' untreated stones versus dyed 'howlite' imitations.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral